Study On Synthesis Of Nonstiochiometric Titanium Carbide Bulk By Spark Palasma Sintering

The purpose of this study is to synthesize nonstoichiometric titanium carbide (TiC_x) bulk with good mechanical properties. The synthesis methods, applications and present problems of titanium carbide (TiC) have been studied and discussed. In order to resolve the brittleness of TiC, the idea of preparing single-phase TiC_x with homogenous microstructure and good densification have been put forward.Firstly, the TiC_x-TiH₂mixed powders were prepared by Mechanical Alloying (MA) with the starting materials of titanium (Ti) powders and toluene. The qualitive and quantitive analysis of ball-milling products were performed by X-Ray Diffraction (XRD) combined with Rietveld refinement. More over, the topography, composition and crystalline of the products were analysed by Transmission Electron Microscope (TEM). Then the mechanism of TiC_x-TiH₂mixed powders synthesization in the process of ball milling was also studied. The results showed that the main phase of the products was TiCx with small amount of TiH₂and Ti left. And then also came the conclusion that the synthesis mechanism of TiC_x-TiH₂belongs to the diffusion type.Then, the process characteristics of spark plasma sintering (SPS) have been studied, and the TiC_x bulks were prepared by SPS with the original mixed powders being TiC_x-TiH₂. The qualitive and structural analysis were realized by XRD combined with Rietveld refinement.More over, the microstructure of the fracture surface was characteried by scanning electron microscopy (SEM). Then the densification and reactive mechanism of TiC_x bulks prepared by SPS technique were discussed. The results show that the obtainment of TiC_x bulks with good densification is realized by SPS with the mixed powders.Compared with traditional sintering methods,the SPS technique is of lower sintering temperature and less time.Finally, the carbon content of TiC_x bulks was obtained by the "oxidation-weighing" method and the density was measured by Archimedes method. Then the hardness and compressive strength were determined by Vickers hardness testor and Gleeble experiment simulator respectively. More over,the relationship between hardness and carbon content, compressive strength and carbon content have been studied. The results show that we gain TiC_o.59, TiC_o.71, TiC_o.74, TiC_o.82, TiC_o.86, TiC_o.89via SPS; the hadness of samples are proportional to carbon content; the compressive strength with increasing carbon content decreases after first increase and it's of deep improvement comparing with other ways.